Add constructors to WebInputEvents and setters so we can work at cleaning up these public structs.

components/test_runner/event_sender.h

Index: components/test_runner/event_sender.h
diff --git a/components/test_runner/event_sender.h b/components/test_runner/event_sender.h
index 6a6d7707a25cb0cff1222a8c6737062f3c4c695f..d8f30b1263c2f6e4e3be44b6d55e532da9159eb1 100644
--- a/components/test_runner/event_sender.h
+++ b/components/test_runner/event_sender.h
@@ -188,10 +188,9 @@ class EventSender {
 
   void UpdateClickCountForButton(blink::WebMouseEvent::Button);
 
-  void InitMouseWheelEvent(gin::Arguments* args,
-                           MouseScrollType scroll_type,
-                           blink::WebMouseWheelEvent* event,
-                           bool* send_gestures);
+  blink::WebMouseWheelEvent GetMouseWheelEvent(gin::Arguments* args,
+                                               MouseScrollType scroll_type,
+                                               bool* send_gestures);
   void InitPointerProperties(gin::Arguments* args,
                              blink::WebPointerProperties* e,
                              float* radius_x,
@@ -199,6 +198,7 @@ class EventSender {
 
   void FinishDragAndDrop(const blink::WebMouseEvent&, blink::WebDragOperation);
 
+  int ModifiersForPointer(int pointer_id);
   void DoDragAfterMouseUp(const blink::WebMouseEvent&);
   void DoDragAfterMouseMove(const blink::WebMouseEvent&);
   void ReplaySavedEvents();